The invention relates to a folded gas bag for a vehicle occupant restraint system.
Gas bags which in an accident have in their inflated state the function of protecting a vehicle occupant from injuries can be arranged folded, usually in a housing, at various points of the vehicle prior to their activation, i.e. their inflation. Above all side gas bags which when inflated cover parts of the side panes of the vehicle to protect the head of the vehicle occupant are often folded up with folds parallel to one another to be accommodated in an elongated housing. Because of the very limited space available the folded gas bag package should be as small as possible.
Following its activation, the gas bag must unfold reliably and rapidly, for which the folding of the gas bag is not least decisive. Up to the present, gas bags are known which are laid in uniform successive folds having equal height, the resulting gas bag package being accommodated in a housing.
It is the object of the present invention to propose a gas bag with a folding reducing the space required by the gas bag package and being able to influence the unfolding of the gas bag.
To this end, in a folded gas bag for a vehicle occupant restraint system the folded gas bag comprises two superimposed walls of the gas bag laid in folds and the folded gas bag is delimited by imaginary first and second fold edge regions. The fold edges of the folds extend in a straight line and parallel to one another. The folds have fold heights measured from one of the fold edge regions and at least two differing fold heights are provided. Hereinafter, a fold is understood to mean a fold edge with the two gas bag sections bordering thereon. In this connection, the distance of a fold edge from a fold edge region of the folded gas bag is referred to as the height of the fold, in contrast to the stack thickness of a fold which in a folded gas bag is defined as the distance between two fold edges on the same fold edge region of the gas bag. The fold edge regions of the folded gas bag are determined by the outer fold edges each. The distance between the fold edge regions can be defined by the maximum distance between two fold edges facing opposing fold edge regions. In the gas bag according to the invention the folds do not necessarily extend from one fold edge region to the other fold edge region of the gas bag package but can also adopt any height which is less than the distance between the two fold edge regions. The advantages of this folding are represented by the possibility of reducing the packing volume of the folded gas bag, also called a gas bag package, and of influencing the exit behavior of the gas bag by a corresponding distribution of the fold heights.
Preferably, the folds lie in planes extending parallel to each other and being vertically stacked. All of the folds of the folded gas bag have preferably fold edges extending parallel to one another.
The fold edge regions are defined by at least some of the fold edges of the gas bag on each side of the folded gas bag. For reasons of clearness here the fold edge regions are taken to be parallel to one another.
In a first preferred embodiment of the invention, the sequence of the height of the folds is chosen such that the fold edges of two successive folds are not directly superimposed. Since in this way two fold edges successive on the same fold edge region are staggered, the volume of the gas bag package is reduced, since because of their radius of curve the fold edges in a gas bag package are bulkier, i.e. they require more space than the gas bag sections therebetween.
It is also possible that on one fold edge region all fold edges of the folded gas bag, which face this fold edge region, are superimposed.
In a further preferred embodiment the sequence of the heights of the folds is chosen such that the center of gravity of the folded gas bag lies adjacent to an imaginary center line of the folded gas bag to influence an exit direction of the gas bag when the gas bag is inflated. In this connection, the sequence of the heights of the folds can be chosen such that e.g. only few fold edges occur on one fold edge region of the folded gas bag whereas many occur on the other fold edge region whereby in the folded state the mass of the gas bag is arranged asymmetrically relative to an imaginary center line which extends in the middle between the two fold edge regions. Since in this way the center of gravity of the gas bag package is placed out of the center line, the exit direction of the gas bag, when inflated, can be different from the center line.
The height of the successive folds preferably corresponds to a repeated sequence of fold heights, wherein at least two of the fold heights are different, to simplify the folding of the gas bag. A preferred sequence consists in the sequence of a deep fold following a flat fold, and another preferred sequence consists in the sequence of several folds becoming continuously flatter. In particular in a combination with the above-mentioned features a wide range of the position of the center of gravity of the gas bag package or, in more general terms, of the shape of the gas bag package can thus be obtained with the least possible packing volume.
Another advantageous application consists in arranging the gas bag within a gas bag module having gas outlet openings and arranging the folds near the gas outlet openings such that they cover the gas outlet openings at least partially. This permits to influence the filling of the gas bag above all in the top region.
The invention is above all suited for side gas bags but can also be used advantageously for front passenger gas bags or any other gas bag which is folded with straight parallel folds.